Dual motion pad sanders



Oct. .13, 1970 sic DUDEK mm. uonou PAD swonas I 2 Sheets-Sheet 1 Filed Nov. 25, 1968 I N VEN TORS am A. Bafson Dudek Edmund C.

. Richard M. Fegan I W TTQRAYIEVY Oct. 13,1970 E. c. DUDEK EI'AL 3,533,193

DUAL MOTION RAD SANDERS Filed Nov. 25, 1968 2 Sheets-Sheet 2 Fig.3

v INVENTORS Fig. 4 W/I/mm A. Bafson c/mund C. 'Dudek WITNESS E Richard M. Fegan ATTORNEY United States Patent 3,533,193 Patented Oct. 13, 1970 US. Cl. 51--170 12 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a dual motion pad sander capable of performing the sanding operation upon a work surface by selectively prescribing either orbital or reciprocatory movement thereon. The pad sander preferably has a direct drive reversible electric motor which drives counter-balanced platens connected through an eccentric and motion changing mechanism whereby in one direction of rotation the platen reciprocates, while in the other direction of rotation the platen is locked to the eccentric to follow an orbital path.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION In accordance with the present invention, the novel dual motion pad sander is provided with a reversible motor mounted in a housing to drive an eccentric which is connected to a platen means through a motion changing mechanism in which for one direction of motor rotation orbital motion is transmitted to theplaten, and in the reverse direction of motor rotation reciproctatory motion is transmitted to the platen.

It is therefore an object of the present invention to provide an improved dual motion pad sander which overcomes the prior art deficiencies; which is simple, economical and reliable; which automatically changes the motion of the platen from orbital to reciprocatory, or vice versa upon reversal of the direction of motor drive; which uses a transverse shifting means mounted to the eccentric drive means and adapted to be selectively locked responsive the direction of drive; which is counterbalanced; which uses a frictionally carried lock means connected to the eccentric to selectively lock the motion changing mechanism; and, which uses a slide bearing mechanism to internally absorb motion in one plane during reciprocation of said sander.

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated in the accompanying drawings in which:

FIG. 1 is a side elevation, partly in section, of a pad sander embodying the present invention,

FIG. 2 is a view taken along line 2-2 of FIG. 1,

FIG. 3 is a View taken along line 3-3 of FIG. 2,

FIG. 4 is a view taken along line 4--4 of FIG. 1,

FIG. 5 is a schematic view representation of the novel dual motion pad sander being driven into a counterclockwise direction to produce orbital motion,

FIG. 6 is an enlarged schematic representation, partly in section, of the present invention in which the drive means is rotated clockwise to produce reciprocatory motion.

DESCRIPTION OF THE INVENTION The present invention is embodied in a pad sander 10, as shown in FIG. 1.

The pad sander 10, illustrated in FIGS. 1 and 2, has a main frame or housing 12, which includes a motor housing 14 mounted atop a base 16, the vertical walls 18 of which define a hollow chamber 20 in which a pair of counterbalanced platens 22 and 24, respectively, are mounted to resilient posts 26 which carry an attachment plate 28 affixed to a support partition 30 of the walls 18. The platen 22 is the lower of the two and carries a resilient pad 32 on the bottom surface thereof. A pair of clamps 34 located at either end of the platen 22 releasably hold a sheet of sand paper (not shown) against the pad 32 for the subsequent sanding operation. The upper platen 24 serves to counterbalance the lower platen 22, and therefore, is offset from the lower platen 22 but otherwise will partake of the same motion, be driven by the same means and have substantially the same mass as the lower platen 22.

The pad sander 10 includes an optional dust pickup system 36 which operates to remove the dust created by the sanding operation by drawing the dust from an annular passage 38 formed between the platen 22 and a skirt 40, into the chamber 20 to be delivered through an integrally formed conduit 42 to a blower (not shown) for discharge from an outlet 44 to the connected collection bag 46 of the dust pickup system 36.

A main handle 48 is connected to the rear of the motor housing 14 and has mounted therein an on-off trigger switch 50 lockable in the on position by a releasable detent pin 52. A reversing switch 54 is mounted on the upper side of the handle 48 adjacent the motor housing 14. A second handle 56 is connected to the front end of the motor housing 14 and permits the operator to firmly grasp the frame 12 of the pad sander 18 both for and aft during the operation and manipulation thereof.

A reversible motor 58 is mounted in the motor housing 14, and connected in circuit with the switches 50 and 54 to a suitable source of electric potential for operation thereof. The motor has an armature 60 and a commutator (not shown) carried by an armature shaft 62 journaled in the housing 12, as by a ball bearing 64. A field 66 is disposed about the armature 60. The commutator is mounted at the upper end of the armature shaft 62 and is operatively engaged by a brush assembly 68. A fan 70 covered by a fan shroud 72 draws air into an inlet 74 to pass in heat exchange relationship to the motor 58 and cools the components thereof prior to being discharged from an outlet 76.

The motor 58 may be of any conventional design, and will be actuated by operation of the switch 50 to turn the shaft 52 clockwise or counterclockwise depending upon which one of two positions the reversing switch 54 has been placed into, whereby on changing the position of the switch 54 the motor and armature shaft thereof will turn in the opposite direction. The lower free end '78 of the armature shaft 62 is of reduced diameter and extends downwardly into the chamber 20 wherein the shaft end connects to a motion changing mechanism which includes a transverse shifting mechanism or slide assembly 82. The motion changing mechanism 80 is clamped to the shaft end 78 between two oppositely disposed eccentric caps 84 and 86, respectively. The

upper cap 84 has a counterbore, the upper section of which is threaded upon the shaft immediately above shaft end 78 to seat against a shoulder 90 formed by the diameter reduction of shaft 62. After the remainder of the motion changing mechanism 80 is assembled a nut 88 is threaded upon the shaft end 78 to abut cap 86. Access to the nut 88 is provided by enlarged central apertures 92 and 94, respectively, formed in the platen 22 and the pad 32 so as to permit relative motion of the platen 22 and shaft 62 without interfering contact occurring between the shaft end 78 and nut 88, and the platen 22 and pad 32.

A separate motion changing mechanism 80 is provided for each of the platens 22 and 24, and except for the eccentric caps 84 and 86 which are positioned 180 out of phase so as to effect the counterbalancing for said platens 22 and 24, and some other minor structural modifications, due mainly to the differences in the platens each of the motion changing mechanisms 80 are identical and therefore, like character references will be used for g each of the mechanisms 80, without a distinction being made for the mechanisms 80 associated with either platen 22 or platen 24.

The caps 84 and 86, respectively, each have pairs of aligned eccentrics 96, all of which are fixedly connected to rotate in the same direction as the rotational direction of the shaft 62, with a counterclockwise direction of rotation being illustrated for FIGS. 1, 2 and 3.

A pair of slide bearings 98 and 100 are fixedly connected to the platens 22 and 24. The bearings 98 and 100 may be formed integrally with the platens 22 and 24, or as is shown in FIGS. 2 and 3 connected by brazing or in any other suitable manner. A lock pin 104 is force fitted to the slide bearing 100 to extend above the upper surface thereof to be normally disposed in a wedge shaped aperture 106 formed in superposition thereto in a lock plate or lever 108 connected through a sleeve bearing 110 to rotatably engage either eccentric 84 or 96, respectively. The lock plate 108 and the sleeve bearing 110 seat upon a wear washer 112, while the upper surface of the lock plate 108 is engaged by a wavy washer 114 suitably mounted in the eccentric 84 or 96, respectively, to act as a loading spring and provide a sulficient frictional engagement between said eccentric and lock plate so as to cause the turning of the lock plate 108 responsive to the direction of rotation of the armature shaft 62.

The lock pin 104 limits the turning of the lock plate 108, as illustrated in FIG. 4 between the apex and base of the aperture 106. counterclockwise rotation of the armature shaft 62 is represented by the full line arrow and will cause the lock plate 108 to turn counterclockwise, thus forcing the lock pin 104 into the apex of the aperture 106 as is represented by the full line drawing of the aperture 106 and the lock plate 108. A clockwise direction of rotation is also illustrated in FIG. 4 by the dotted arrow and dotted representation of the aperture 106 and lock plate 108 for which the lock pin 104 acts to limit the clockwise turning of said plate upon abutting the substantially flat base of the wedge shaped aperture 108. The purpose of providing a turnable lockplate 108 will be set forth hereinafter.

The slide bearings 98 and 100 have central apertures 116 and 118, respectively, formed perpendicular to the longitudinal axis of the shaft 62 and its end 78, while the longitudinal axis of said apertures extends parallel to and transversely of the platens 22 and 24. Below the wear washer 112 and a ball bearing 120 is seated at its inner race upon one of the eccentrics 96 to be clamped between said eccentric and one of the end caps 84 or 86. The outer race of the bearing 120 seats upon the inner periphery of a bearing collar 122 which has diametrically opposed transverse projections formed at either end thereof. Each of the projections formed has an aperture 124 the axis of which is in line with the axis of the re- 4 spective apertures 116 and 118. A slide pin 126 is fixedly connected in the aperture 124 to extend radially outwardly therefrom to be slidingly engaged within the respective apertures 116 and 118.

When the armature shaft 62 is rotated counterclockwise the spring loaded wavy washer 114 will frictionally engage the lockplate 108 causing it to turn counterclockwise whereby the lock pin 104 will abut the apex of the wedge shaped aperture 106 for the dual purpose of limiting the counterclockwise turning of the lock plate 108, and preventing transverse motion of the slide pin 126 in the respective slide bearings 98 and 100. So long as the lock pin 104 is retained in the apex of the aperture 106 no transverse motion of the slide pin 126 is possible. However, the slide pin 126 is always transmitting longitudinal motion and therefore aids the turning momentum of the lock plate 108 in retaining the lock pin 104 in the apex of the aperture 106. Thus, as seen in FIGS. 2, 3, 4 and 5, the counterclockwise rotation of the armature shaft 62 results in the motion changing mechanism partaking of the orbital motion of the armature shaft 62 as transmitted by the eccentrics thereof, as is illustrated in FIG. 5.

Assuming an initial counterclockwise direction of rotation actuation of the reversing switch 54 will cause the motor 58 to rotate the armature shaft 62 in a clockwise direction resulting in the motion changing mechanism 80 transforming the rotary motion of the shaft 62 into reciprocatory motion at the respective platens 22 and 24. Upon clockwise rotation of the armature shaft 62 the lock plate 108 represented in FIG. 4 by the dotted linear lines will be turned clockwise through the frictional urgings of the wavy washer 114, thus freeing said plate from the lock pin 104 which still acts to limiting the turning of the lock plate 108 by abutting the base of the wedge shaped aperture 106. Said base has a transverse dimension substantially twice that of the eccentricity of the eccentrics 96 so as not to interfere with the relative motion of the pin 104 and the lock plate 108. The rotary motion transmitted from the armature shaft 62 to the respective platens 22 and 24 may be characterized by a longitudinal component lying in the direction of reciprocation and a transverse component lying perpendicular to the direction of reciprocation. As the shaft 62 rotates there is nothing to interfere with or absorb the longitudinal component of the motion thereof, and this component is transmitted directly through the eccentrics 96 to the bearing collar 122, slide pin 126, slide bearings 98 and to cause the respective platens 22 and 24 to reciprocate as indicated by the dotted arrows and in phantom representation of said platen shown in FIG. 6. However, this is not the case for the transverse component of the motion, which component is absorbed in the transverse shifting mechanism or slide assembly 82 of the motion changing mechanism 80. In FIG. 6 the full line representation of the motion changing mechanism 80 depicts the transverse component of the motion at leftward extreme of its travel, that being the leftward most travel, with the rightward extreme of said travel indicated by the dotted representation of the aperture 106, the eccentric 96 and the slide pin 126.

As the eccentric rotates any transverse component of motion is transferred through the bearing collar 122 to the slide pin 126 which slidingly engages the slide bearings 98 and 100, respectively, so that no transverse component of the motion is transmitted to the platens 22 and 24. In other words, as the eccentric 96 is rotated by the armature shaft 62 the pins 126 are alternately shifted from right to left to slide within the apertures of the slide bearings 98 and 100 while pushing said slide bearings and the connected respective platens 22 and 24 back and forth to accomplish the reciprocatory motion thereof. During clockwise rotation of the armature shaft 62 the lock pin 104 remains free within the aperture 106,

the base of which slides transversely along the pin 104, so that the transverse shifting mechanism 82 of the motion changing mechanism 80 remains in an unlocked position and is free to absorb the transverse component of the rotary motion of the eccentrics 96.

The motion changing mechanism 80 may be generally described as including all of the components connected to the armature shaft 62 and shaft end 78, except for possibly the platens 22 and 24. The transverse shifting mechanism 82 of the motion changing mechanism 80 relates to the components which absorb the transverse motion of the eccentric 96, and therefore, may be said to exclude the lock plate 108.

In summary, the operator desiring orbital motion will position the switch 54 to obtain counterclockwise rotation of the armature shaft 62 of the motor 58, which rotation will act to lock the transverse shifting mechanism 82 to the lock plate 108 whereby the rotary motion of the eccentrics 96 will be transmitted to said members directly to the platens 22 and 24 for counterbalanced orbital motion thereof. Reciprocatory motion will be obtained by the operator changing the position of the reverse switch 54 to cause clockwise rotation of the armature shaft 52, thus turning the lock plate to a second or unlocked position whereby the transverse shifting mechanism 82 is free to absorb the transverse component of the motion and to transmit the longitudinal component of the motion so as to cause the platens 22 and 24 to reciprocate in a counterbalanced fashion, and thus produce a straight line motion thereof. Accordingly, by merely actuating the reversing switch 54 the operator will obtain either orbital motion or reciprocatory motion for the platens of the pad sander 10.

It will be understood that various changes in the details, materials, arrangements of parts and operating conditions which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the claims.

Having thus set forth the nature of the invention, what is claimed herein is:

1. In a counterbalanced pad sander adapted to prescribe orbital motion or reciprocal motion upon a fiat work surface, the combination of:

(a) ahoursing,

(b) a reversible motor mounted in the housing,

() an eccentric drive means rotatably driven by the motor along an axis perpendicular to the work surface,

(d) a platen means supported in the housing to be driven by the eccentric drive means to prescribe translatory movement upon said work surface in an orbital or reciprocal path,

(e) a motion changing mechanism connected between the eccentric drive means and the platen means,

(f) the motion changing mechanism including, a transverse shifting means, and a locking means interconnected thereto, and

(g) the transverse shifting means to remain unlocked in one direction of rotation of said drive means to transmit the reciprocal motion thereof to the platen while internally absorbing motion perpendicular to the direction of reciprocation, and in the other direction of rotation of said drive means to be locked thereto by the locking means to transmit the orbital motion thereof to the platen.

2. The combination claimed in claim 1 wherein:

(a) an upper transverse shifting means, locking means and platen means carried by the eccentric drive means, and

(b) a lower transverse shifting means, locking means and platen means carried by the eccentric drive means 180 out of phase with said upper unit to counterbalance the motion of the pad sander and reduce vibration.

3. The combination claimed in claim 1 wherein:

(a) the eccentric drive means including a shaft and a connected eccentric means.

4. The combination claimed in claim 3 wherein:

(a) the shaft is directly driven by the motor.

5. The combination claimed in claim 4 wherein:

(a) the locking means frictionally carried by the cocentric means, and

(b) means formed on the locking means, to limit the turning motion thereof between two positions in one position of which permits the transverse shifting means to move perpendicular to the direction of reciprocation, and in another position of which the transverse shifting means is locked through the locking means for direct connection with the eccentric means to transmit the orbital motion thereof, and

(c) the transverse shifting means partaking of motion perpendicular to the direction of reciprocation defined as transverse shifting.

6. The combination claimed in claim 5 wherein:

(a) the transverse shifting means including a slide pin portion slidably received in a bearing portion thereof,

(b) the slide pin portion rotatably mounted onto the eccentric means,

(c) the bearing portion affixed to the platen means and carrying a lock pin,

(d) the locking means having a wedge shaped aperture formed to have the lock pin extend therein,

(e) the lock pin in one direction of rotation of said drive means positioned in the wide end of the aperture to permit transverse shifting of the transverse pin portion within the bearing portion of the transverse shifting means to produce reciprocal motion at the platen, and upon reversal of said direction of rotation the aperture to shift with the locking means to lock the pin in the narrow edge thereof to prevent transverse shifting and to cause orbial motion to be transmitted by the transverse shifting means to said platen.

7. In a direct drive pad sander, the combination of:

(a) a housing,

(b) a reversible motor mounted in the housing,

(c) an eccentric drive means operatively driven by the motor,

(d) a motion changing mechanism, in one direction of drive to transmit orbital motion and in the reverse direction of drive to transmit reciprocatory motion,

(e) a platen means mounted onto the motion changing mechanism to prescribe a path of motion responsive to the position of said mechanism.

8. The combination claimed in claim 7 wherein the pad sander is counterbalanced and includes:

(a) an upper motion changing mechanism and connected platen and (b) a lower motion changing mechanism and connected platen substantially out of phase with the upper of said phase mechanisms.

9. The combination claimed in claim 8 wherein each of the motion changing mechanisms includes:

(a) a slide assembly rotatably mounted to the drive means and fixedly connected to said platen, the slide assembly to transmit motion in the direction of reciprocatory motion and independently move in a plane parallel to the work surface perpendicularly to the line of reciprocation,

(b) locking means frictionally connected to the eccentric drive means and interconnected to the slide assembly, in one direction of rotation to lock said slide assembly from independent motion to produce orbital motion at the platen, and upon reversal of the direction of rotation to unlock said slide assembly to permit said independent motion to produce reciprocal motion at the platen.

10. The combination claimed in claim 9 wherein:

(a) the locking means including a plate having a Wedge shaped substantially longitudinal slot formed adjacent one end thereof,

(b) a pin connected to the slide assembly extending into said slot, and

(c) the pin limiting the turning movement of the plate and in one direction of rotation freely movable in said slot, and in the reverse direction of rotation nonmovably held in the slot to cause the slide assembly to be locked to the eccentric drive means.

11. The combination claimed in claim 1 wherein: (a) the platen is resiliently supported by the housing. 12. The combination claimed in claim 8 wherein:

(a) each of the platens is resiliently supported by the housing.

References Cited UNITED STATES PATENTS WILLIAM R. ARMSTRONG, Primary Examiner 

